Providing seamless services is a critical issue for mobile networks. In the context of services supported by the Internet protocol (IP), seamless IP-layer connectivity is necessary as a mobile terminal hands off to a new access router with minimal disruption to the mobile terminal's Internet connectivity. There are several approaches to providing IP connectivity. First, the mobile IP protocol describes a mechanism that allows packets to be routed through the Internet to a new access router when the mobile terminal changes its point of attachment to the Internet from an old access router to the new access router. Also, after having established link-layer connectivity with the new access router, the mobile terminal engages in signaling the new access router in order to obtain its new care-of-address. When obtaining the new care-of-address the mobile terminal has acquired IP-level connectivity with the new access router so that the mobile terminal can transmit and receive packets with the new access router. A fast handoff protocol enables forming the new care-of-address while the mobile terminal is still attached to the old access router. As soon as the mobile terminal acquires link-layer connectivity with the new access router, the mobile terminal can transmit and receive packets with the new access router.
Moving the mobile terminal's point of attachment to the Internet from the current access router to the new access router may not suffice to provide seamless service if the mobile terminal's application requires additional features for packet transport such as transport quality of service (QoS), security, and header compression. These features need to be provided at the new point of mobile terminal's attachment to the Internet after IP-layer handoff. This can be achieved via context transfer framework.
Current approaches to a context transfer framework limit solutions to seamless IP-layer connectivity and do not address the service and business related aspects. In other words, ability to exchange packets with the Internet in an uninterrupted fashion in the light of handoffs as considered by current approaches, does not necessarily mean that the multimedia application on the mobile terminal will continue seamlessly. This is because, applications may make use of certain application-specific network functionalities, which may need to be relocated or provisioned concurrently with IP-layer handoffs.
For example, a mobile terminal (mobile node) may be accessing an Internet application that is provided by a content source such as line navigation, which depends upon the mobile terminal's geographical location. Typically, the content source uses a supplementary service provider functionality that is specific to the network serving the mobile terminal. In the case of a location service, for example, selecting the supplementary service provider functionality according to the serving network may be necessitated by the dependence of radio access technology that the mobile terminal is utilizing (global positioning satellites, time difference of arrival, angle difference of arrival, RF badges, and so forth) as well as by the physical wireless environment (e.g. indoor or outdoor). Moreover, the supplementary service provider functionality is accessing highly confidential data, namely the mobile terminal's location, and hence the supplementary service provider functionality has a special trust relationship with the administrative entity of the network domain that is serving the mobile terminal.
If the mobile terminal hands off to another administrative domain, either by migrating to another network operator that uses the same radio technology as the previous network operator or by switching to another radio access technology of another network operator, the current supplementary service provider functionality may not be able to provide mobile terminal's location information to customize the content from the content source to the mobile terminal. Even though the mobile terminal may experience seamless IP-network connectivity, an application that the mobile terminal is utilizing before the handoff may not he able to continue after the IP-level handoff because the content source does not have access to an appropriate supplementary service provider functionality. Hence, with the increasing importance of supporting enhanced services to a mobile terminal over the Internet, there is a need to support application-specific functionality in a seamless manner.